If she becomes incompetent I would have to make choices for her that she has expressed she does not want. I am not so sure I could handle the guilt about going against her wishes.
Labs, you do know that you cannot be forced to do any hands on care for your mother or to have her in your home, right? One idea mentioned on his forum is when she needs to go the emergency room, you refuse to take her home. It is an unsafe placement since your medical problems prevent you from doing any care and her home is not safe because of health hazards. The hospital social workers then find her a placement. An option is for her to become a ward of the state. Love her, but stand clear - no way can you or any non-professional fix the mess.